When the total solar eclipse begins around 10 a.m. on August 21, its path will start in Oregon and ending in South Carolina. Along the way, certain areas and towns have been designated by scientists as the best place to view this feat of nature.

In all, 12 states are in the totality path to this point. And places in the totality path are expected to attract up to tens of thousands of people who come to view the eclipse as well as enjoy the many festivals that will be held during the solar event.

Small towns of less than 10,000 may be overrun with more than 50,000 visitors, some of whom may have to stay in hotels two hours away to see this phenomenon. Rural areas with wide-open spaces are the best, such as Marshall, Missouri.

These eclipse chasers plan for years to attend the best viewing spots, spending time charting the eclipse with maps, and visiting forums and social media.

OK, so all this is very interesting, but what does it have to do with mysteries?

A month or so ago, I would have wondered the same thing until I read the brilliant thriller He Said/She Said (Minotar) by Erin Kelly.

These eclipse chasers, who relish “celestial mechanics,” provide the background for this innovative mystery. While Kelly includes plenty of lore about seeing an eclipse, the author also delivers an unusual psychological thriller about a marriage, as well as obsessions, secrets, and how rape is viewed.

At first glance, it would seem that eclipses are about an insular community of people who travel great distances to watch. But He Said/She Said shows that it’s not just a small group but a wide swath of people, some of whom have never seen an eclipse and others who have no interest in the science behind it.

Christopher “Kit” McCall has chased solar eclipses his entire life, and considers “real life as the boring bit between eclipses.” Kit and his girlfriend, Laura Langrishe, are celebrating the 1999 solar eclipse at a festival in Cornwall when they stop the apparent rape of a stranger. The lives of Kit and Laura are entwined for years in the lives of the victim and her abuser.

He Said/She Said alternates between 1999 and 16 years later when Kit and Laura are married and expecting twins. Now another eclipse looms, and the best place to view is the Faroe Islands. Kit will go while Laura stays home because of her advanced pregnancy.

The eclipse is an exciting background to He Said/She Said as Kelly adds enough science and sky lore to make readers want to rush out to get those glasses one is supposed to wear during a viewing. But Kelly never allows the science to overwhelm her unusual thriller.